Pump-free water-cooling system

ABSTRACT

A pump-free water-cooling system is provided wherein external power supply is not involved; heat can be transported in any direction; and high reliability and low thermal resistance are ensured. 
     The pump-free water-cooling system includes: a heat-exchange circulating solution container in which a heat-exchange circulating solution and vapor of the circulating solution are contained; a heat radiator provided on the outer wall of the container; a solution outlet for discharging from the container the heat-exchange circulating solution in the container; a gas-liquid two-phase fluid inlet for charging into the container gas-liquid two-phase fluid composed of the heat-exchange circulating solution at high temperature and vapor bubbles of the circulating solution; a first transportation route along which a sensible-heat-emitting heat exchanger is provided, the first transportation route linking with the solution outlet; a second transportation route along which heat exchange is carried out between heat-exchange circulating solution therein and the heat-exchange circulating solution in the container and the vapor of the heat-exchange circulating solution in the container; a third transportation route along which a heating heat exchanger is provided, the third transportation route linking with the gas-liquid two-phase fluid inlet; and a circulating-solution transporting route in which the first transportation route, the second transportation route, and the third transportation route are linked in that order.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of and claims the benefit of priorityunder 35 U.S.C. § 120 from U.S. Ser. No. 11/008,245, filed Dec. 10,2004. This application also claims the benefit of priority under 35U.S.C. § 119 from Japanese priority documents 2004-001030 filed in Japanon Jan. 6, 2004.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to heat transporting apparatus, moreparticularly to a pump-free water-cooling system that requires noexternal power supply such as a mechanical pump.

2. Description of the Related Art

In recent years, the calorific values of electronic apparatuses haverapidly been increasing; therefore, higher-efficiency heat radiatingmeans have been required. In addition, the life times of the electronicapparatuses have been prolonged; therefore, higher-reliability heatradiating means have been required. Under this background, heat pipeswithout moving parts (e.g., refer to Patent Reference 1) have beendrawing attention again. Heat pipes are roughly divided into two types,i.e., gravity-type heat pipes (thermosiphon) and capillary-type heatpipes. In a gravity-type heat pipe, an appropriate amount of workingfluid is enclosed in an airtight container; and the lower portion of thegravity-type heat pipe joins with a heating element while its upperportion joins with a heat radiating portion, or is directly disposed incooling fluid. In contrast, in a capillary-type heat pipe, anappropriate amount of working fluid is enclosed in an airtight containerwith grooves on its inner wall, or in an airtight container with poroussubstance covering its inner wall; and one end of the capillary-typeheat pipe joins with a heating element while the other end joins with aheat radiating portion, or is directly disposed in cooling fluid.

Because the capillary-type heat pipe that has the structure describedabove refluxes working fluid to a heating portion (a portion in which aheating element is disposed) by means of capillary force, i.e.,extremely small driving force, its maximal heat transportation capacityis small, and it is difficult to reflux the working fluid in thedirection reverse to gravity direction; therefore, the problem ofdifficulty in transporting heat has been posed. In contrast, because agravity-type heat pipe refluxes working fluid to a heating portion byutilizing gravity, there was limitation of posture, i.e., that the heatradiating portion must definitely be situated higher than the heatingelement; therefore, a problem has been posed wherein there was no degreeof freedom in terms of installation posture.

SUMMARY OF THE INVENTION

The present invention has been implemented in order to address theforegoing issues, and it is an object to provide a high-reliability,low-thermal-resistance pump-free water-cooling system that requires noexternal power supply, that allows heat to be transported in anydirection, and that has large heat transportation capacity and lowerthermal resistance.

A pump-free water-cooling system according to the present inventionincludes: a heat-exchange circulating solution container in which aheat-exchange circulating solution and vapor of the circulating solutionare contained; a heat radiator provided on the outer wall of thecontainer; a solution outlet for discharging from the container theheat-exchange circulating solution in the container; a gas-liquidtwo-phase fluid inlet for charging into the container gas-liquidtwo-phase fluid including the high-temperature heat-exchange circulatingsolution and vapor bubbles of the circulating solution; a firsttransportation route along which a sensible-heat-emitting heat exchangeris provided, the first transportation route linking with the solutionoutlet; a second transportation route along which heat exchange iscarried out between the heat-exchange circulating solution therein andthe heat-exchange circulating solution in the container, or between theheat-exchange circulating solution therein, and the heat-exchangecirculating solution in the container and the vapor of the heat-exchangecirculating solution in the container; a third transportation routealong which a heating heat exchanger is provided, the thirdtransportation route linking with the gas-liquid two-phase fluid inlet;and a circulating-solution transporting route wherein the firsttransportation route, the second transportation route, and the thirdtransportation route are linked in that order.

In the pump-free water-cooling system according to the presentinvention, when the heat-exchange circulating solution receives in thethird transporting route heat from the heating heat exchanger, theheat-exchange circulating solution raises its temperature; boilingoccurs in the third transporting route, thereby producing vapor bubbles;and the heat-exchange circulating solution and the vapor bubbles travelthrough the circulating-solution transporting route by means of thebuoyant force that acts on the vapor bubbles. Traveling of the vaporbubbles causes part of the heat received from the heating heat exchangerto be radiated through the heat radiator provided on the outer wall ofthe heat-exchange circulating solution container. In addition, travelingof the heat-exchange circulating solution causes the remaining portionof the heat received from the heating heat exchanger to be radiatedthrough the sensible-heat-emitting heat exchanger. In conventionalgravity-type heat pipes, the latent heat transportation by means ofvapor bubbles to the heat radiating portion is performed merely asdescribed herein; in contrast, in the present invention, the latent heattransportation by means of vapor bubbles to the heat radiator and thesensible heat transportation by means of circulating solution to thesensible-heat-emitting heat exchanger is performed, whereby a largeamount of heat can be transported. Moreover, because the heattransportation to the sensible-heat-emitting heat exchanger is performedmerely by means of liquid, it is not required to provide thesensible-heat-emitting heat exchanger above the heating heat exchanger;therefore, the sensible-heat-emitting heat exchanger can be provided atany position, whereby the degree of freedom in terms of a heat-radiationposition increases.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 1 of the present invention;

FIG. 2 is a cross-sectional schematic view illustrating anotherpump-free water-cooling system according to Embodiment 1 of the presentinvention;

FIG. 3 is a cross-sectional schematic view illustrating anotherpump-free water-cooling system according to Embodiment 1 of the presentinvention;

FIG. 4 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 2 of the present invention;

FIG. 5 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 3 of the present invention;

FIG. 6 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 4 of the present invention;

FIG. 7 is a cross-sectional schematic view illustrating anotherpump-free water-cooling system according to Embodiment 4 of the presentinvention;

FIG. 8 is a cross-sectional schematic view illustrating anotherpump-free water-cooling system according to Embodiment 4 of the presentinvention;

FIG. 9 is a cross-sectional schematic view illustrating anotherpump-free water-cooling system according to Embodiment 4 of the presentinvention;

FIG. 10 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 5 of the present invention;

FIG. 11 is a cross-sectional schematic view illustrating anotherpump-free water-cooling system according to Embodiment 5 of the presentinvention;

FIG. 12 is a cross-sectional schematic view illustrating anotherpump-free water-cooling system according to Embodiment 5 of the presentinvention;

FIG. 13 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 6 of the present invention;

FIG. 14 is a view illustrating a bubble nucleus involving Embodiment 6of the present invention;

FIG. 15 is a view illustrating another bubble nucleus involvingEmbodiment 6 of the present invention;

FIG. 16 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 7 of the present invention;

FIG. 17 is a perspective view illustrating a pump-free water-coolingsystem according to Embodiment 8 of the present invention;

FIG. 18 is a cross-sectional schematic view illustrating a heating heatexchanger and a rack wall according to Embodiment 8 of the presentinvention;

FIG. 19 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 9 of the present invention;and

FIG. 20 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 10 of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1

Embodiment 1 of the present invention will be discussed below referringto the accompanying drawings.

FIG. 1 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 1 of the present invention.FIG. 2 is a cross-sectional schematic view illustrating anotherpump-free water-cooling system according to Embodiment 1 of the presentinvention. In FIG. 1, a heat-exchange circulating solution container 4contains a high-temperature heat-exchange circulating solution 1 andhigh-temperature vapor 12 that is produced by phase change of thesolution 1 and has latent heat. In addition, a heat radiator 2 isdisposed on the outer wall of the heat-exchange circulating solutioncontainer 4, whereby the heat of the heat-exchange circulating solution1 and the vapor 12 is radiated to the heat radiator 2. In thissituation, the vapor 12 is condensed into the heat-exchange circulatingsolution 1 successively. Moreover, in Embodiment 1, the wall surface ofthe heat-exchange circulating solution container 4 plays a role as aheat transferring wall for exchanging heat with the heat radiator, andthus fins may be disposed inside or outside the wall surface. Stillmoreover, the heat radiator 2 may be constituted as illustrated in FIG.2, i.e., in such a manner that part of the outer wall of theheat-exchange circulating solution container 4 is protruded into thesurroundings; fins are provided on the protruded outer wall; andfurther, the heat may be radiated by means of a fan 3.

The heat-exchange circulating solution container 4 is provided with asolution outlet 5 through which the heat-exchange circulating solution 1in the container 4 is discharged. The heat-exchange circulating solutioncontainer 4 is also provided with a gas-liquid two-phase fluid inlet 8through which gas-liquid two-phase fluid consisting of the heat-exchangecirculating solution 1 and vapor bubbles 13 of the heat-exchangecirculating solution 1 flows into the container 4. Still moreover, dueto the influx of the gas-liquid two-phase fluid, the heat-exchangecirculating solution 1 in the heat-exchange circulating solutioncontainer 4 and the condensed liquid that is produced by condensing thevapor 12 are agitated.

The heat-exchange circulating solution 1 may preferably be such liquidsas have high-heat characteristics (e.g., having high heat conductivityor high specific heat), good hydrodynamic characteristics (e.g., havingsmall viscosity coefficient), and large density ratio of liquid to gas,and the liquid that is utilized is single-ingredient liquid such asdistilled water, alcohol, or liquid metal, antifreeze solution, oil,water solution such as alcohol solution, magnetic fluid, or the like,and exhibits phase change between gas and liquid. The vapor 12, which isthe totally or partially gasified heat-exchange circulating solution 1,may be mixed with noncondensable gas such as air.

The solution outlet 5 provided in the heat-exchange circulating solutioncontainer 4 and the gas-liquid two-phase fluid inlet 8 are linkedthrough a circulating-solution transporting pipe A, whereby thecirculating-solution transporting path through which the heat-exchangecirculating solution 1 circulates is constituted.

The circulating-solution transporting pipe A includes a solutiondischarging pipe (the first transportation route) 6 connected to thesolution outlet 5, inner-container pipes (the second transportationroute) 7 that pass through the heat-exchange circulating solutioncontainer 4, a gas-liquid two-phase fluid charging pipe (the thirdroute) 9 connected to the gas-liquid two-phase fluid inlet 8; theheat-exchange circulating solution 1 exits from the container 4 andreturns to the container 4 after passing through the solutiondischarging pipe 6, the inner-container pipes 7, and the gas-liquidtwo-phase fluid charging pipe 9, in that order.

Moreover, the solution outlet 5 is for discharging the high-temperatureheat-exchange circulating solution 1; however, if the vapor bubbles 13flow along with the heat-exchange circulating solution 1 into thesolution outlet 5, buoyant force acts in the direction reverse to thecirculating direction of the heat-exchange circulating solution 1,whereupon the circulating flow volume of the heat-exchange circulatingsolution 1 is decreased; therefore, wire gauze or a blocking plate eachopening of which has a diameter the same as, or smaller than, that ofthe vapor bubbles 13 may be disposed in the solution outlet 5 in orderto prevent the vapor bubbles 13 from flowing in.

Still moreover, the gas-liquid two-phase fluid-charging pipe 9 mayprotrude into the heat-exchange circulating solution container 4. Inthis manner, larger buoyant force is generated, thereby increasing thecirculating flow volume of the heat-exchange circulating solution 1, andraising heat transportation capacity.

In the circulating solution transporting pipe A, the solutiondischarging pipe 6 is provided with a sensible-heat-emitting heatexchanger 10, thereby radiating through the pipe wall the heat of thecirculating solution that circulates through the solution dischargingpipe 6. Moreover, the gas-liquid two-phase fluid-charging pipe 9 isprovided with a heating heat exchanger 11, whereby the circulatingsolution that circulates through the solution discharging pipe 6 absorbsheat through the pipe wall and is heated up.

The heating heat exchanger 11 is a heating element such as an electronicapparatus or a heat-radiating portion of an apparatus that transportsheat from the heating element; the heat radiator 2 and thesensible-heat-emitting heat exchanger 10 are heat-receiving portions ofheat transportation apparatuses, such as a refrigerating-cycle apparatusand a heat pipe, or heat-radiating walls that utilize natural- andforced-convection heat transfer and radiation. In addition, instead ofproviding the heating heat exchanger 11, the sensible-heat-emitting heatexchanger 10, and heat radiator 2, the gas-liquid two-phase fluidcharging pipe 9 on which the heating heat exchanger 11 is disposed, thesolution discharging pipe 6 on which the sensible-heat-emitting heatexchanger 10 is disposed, and the heat-exchange circulating solutioncontainer 4 on which the heat radiator 2 is disposed may be installeduncovered directly in any space (such as, in the air, in the water, andin the soil) and may be heated up or made to radiate, by means of heatconduction, natural- and forced-convection heat transfer, and radiation.In that case, fins or the like may be disposed on the heat radiatingwalls or on the surface of the uncovered portions. Still moreover,blowing wind may be utilized as a cooling method for the heat radiator 2and the sensible-heat-emitting heat exchanger.

Further moreover, the number of the heating heat exchanger 11 and thesensible-heat-emitting heat exchanger 10 that are disposed along theflowing path may be pluralized.

The circulating-solution transporting pipe A is a path includingcircular tubes for transferring the heat-exchange circulating solution1, elliptical tubes, rectangular tubes, and corrugated tubes (flexibletubes). In addition, in the circulating solution transporting pipe A,the wall surface of the gas-liquid two-phase fluid charging pipe 9 onwhich the heating heat exchanger 11 is disposed, the wall surface of thesolution discharging pipe 6 on which the sensible-heat-emitting heatexchanger 10 is disposed, and the wall surface of the inner-containerpipe 7 play a role as heat transferring wall for exchanging heat; eachof the pipes may be provided inside with a turbulence facilitator forfacilitating heat transfer, a spiral flow facilitator (e.g., a twistedtape), or fins, and may be a spiral tube or a meandering pipe in orderto increase the heat-transferring area per unit volume. Moreover, theinner-container pipe 7 is to exchange heat between the heat-exchangecirculating solution 1 inside the inner-container pipe 7, and theheat-exchange circulating solution 1 and the vapor 12 outside theinner-container pipe 7, and may be provided on its external wall surfacewith fins or the like.

Meanwhile, heat-insulating materials may be provided on the externalwall surface, other than each foregoing wall surface, of thecirculating-solution transporting pipe A.

The operation of a heat transportation apparatus according to Embodiment1 will be described below. The heat-exchange circulating solution 1 thatis enclosed in the heat-exchange circulating solution container 4 andthat holds high-temperature heat circulates within the apparatus whileflowing through the circulating-solution transporting pipe A; thehigh-temperature heat-exchange circulating solution 1, upon passingthrough the solution discharging pipe 6 of the circulating-solutiontransporting pipe A, radiates its sensible heat and exchange the heatthrough the sensible-heat-emitting heat exchanger 10, thereby beingcooled to a low temperature. The low-temperature heat-exchangecirculating solution 1, upon passing through the inner-container pipe 7after being cooled, is preheated by the high-temperature heat-exchangecirculating solution 1 enclosed in the heat-exchange circulatingsolution container 4, or by the high-temperature heat-exchangecirculating solution 1 and the vapor 12 of the circulating solution,thereby raising its temperature. The temperature-raised heat-exchangecirculating solution 1 is further heated up to a high temperature by theheating heat exchanger 11, thereby boils, and returns to theheat-exchange circulating solution container 4 while generating thevapor bubbles 13. The heat-exchange circulating solution 1 that hasreturned to the heat-exchange circulating solution container 4 and thevapor bubbles 13 (becoming the vapor 12) radiate heat to the heatradiator 2 disposed on the outer wall of the heat-exchange circulatingsolution container 4, whereupon the vapor 12 is condensed into theheat-exchange circulating solution 1 continuously. In addition, theheat-exchange circulating solution 1 that has returned to theheat-exchange circulating solution container 4 again flows through thecirculating-solution transporting pipe A, thereby experiencing in cyclescooling, preheating, and temperature raising to the boiling temperature.

In the heat transportation apparatus according to Embodiment 1, theheat-exchange circulating solution 1 is made to circulate within theapparatus by utilizing the density difference (buoyant force produced bythe density change), in the circulating-solution transporting pipe A,that is produced by phase change of the heat-exchange circulatingsolution 1. In other words, by utilizing the density difference betweenthe apparent density of the gas-liquid two-phase fluid between theheating heat exchanger 11 and the gas-liquid two-phase fluid inlet 8,within the gas-liquid two-phase fluid charging pipe 9, and the densityof the heat-exchange circulating solution 1 in the same longitudinallength as that between the heating heat exchanger 11 and the gas-liquidtwo-phase fluid inlet 8, within the circulating-solution transportingpipe A, the heat-exchange circulating solution 1 is made to circulate.Moreover, by repeating this circulation, the heat transferred by theheating heat exchanger 11 is transported to the sensible-heat-emittingheat exchanger 10 and the heat radiator 2, and then thesensible-heat-emitting heat exchanger 10 and the heat radiator 2 aremade to transport the heat to other heat-requiring apparatuses or heatsink.

In addition, in Embodiment 1, with regard to positional relationshipamong the heat-exchange circulating solution container 4, thesensible-heat-emitting heat exchanger 10, and the heating heat exchanger11, the heating heat exchanger 11 is merely required to be situatedbelow the heat-exchange circulating solution container 4; anyrelationship other than between the heating heat exchanger 11 and theheat-exchange circulating solution container 4 may be different fromthat in the present embodiment. For instance, the sensible-heat-emittingheat exchanger 10 may be situated above the heating heat exchanger 11and the heat-exchange circulating solution container 4.

Moreover, when the distance between the heating heat exchanger 11 andthe two-phase fluid inlet 8 of the heat-exchange circulating solutioncontainer 4 is sufficiently long, the buoyant force that acts on theheat-exchange circulating solution 1 in a pipe 9 a corresponding to theforegoing distance allows the heat-exchange circulating solution 1 tocirculate; therefore, the heating heat exchanger 11 can be disposedhorizontally.

FIG. 3 is a cross-sectional schematic view illustrating a pump-freewater-cooling system with the heating heat exchanger 11 disposedhorizontally. This manner makes horizontal-plane heat transportationpossible.

In this case, it is more preferable that the heating heat exchanger 11has its exit side slightly lifted above the horizontal axis thereof.

In FIG. 3, boiling starts from the portion on which the heating heatexchanger 11 is disposed; however, the boiling may not occur in theportion on which the heating heat exchanger 11 is disposed, but mayoccur in the pipe 9 a. This kind of boiling is referred to as flashvaporization; and the above phenomenon occurs because the boiling doesnot occur in the lower side due to high pressure caused by high headpressure but starts to occur in the upper side, because the higherposition in the pipe the head pressure is lower, whereby the upper sideis subject to the lower pressure (the same as or lower than thesaturation pressure of the liquid). Even in this situation, theheat-exchange circulating solution 1 can circulate by means of thebuoyant force that acts on the heat-exchange circulating solution 1 inthe pipe 9 a; therefore, the heating heat exchanger 11 can be disposedhorizontally.

As discussed above, in the heat transportation apparatus according tothe present embodiment, the heat-exchange circulating solution, withoututilizing external power supply, continuously circulates within theapparatus by taking advantage of the density difference in theheat-exchange circulating solution, a large amount of heat can betransported in any directions (such as horizontally, from a lower to ahigher position, and from a higher to a lower position). In addition,long-distance heat-transportation is also possible. Moreover, the heattransportation apparatus is durability- and reliability-affluent,compact, and lightweight because it does not have any pump with a movingelement.

Still moreover, heat radiation by two type of heat-radiating portionsraises the heat transportation capacity, thereby decreases the thermalresistance. Furthermore, even in the case where heat load supplied bythe heating heat exchanger is small, the vapor 12 is condensed by theheat radiator; therefore, the gas-liquid two-phase fluid in the thirdtransportation route can readily move, whereby the stable circulation ofthe heat-exchange circulating solution is caused, and thus unstableoperation such as pulsation of the solution circulation can hardly beproduced. Still furthermore, because the continuous circulation occurs,and vapor bubbles that flow into the heat-exchange circulating solutioncontainer agitate the heat-exchange circulating solution and thecondensed liquid produced by condensing vapor, multi-component fluidutilized as the heat-exchange circulating solution does not cause anylocal density hikes, thereby causing no mal-operation such as elevationof the boiling point.

Embodiment 2

FIG. 4 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 2 of the present invention.In a pump-free water-cooling system according to Embodiment 2 of thepresent invention, as illustrated in FIG. 4, the heat-exchangecirculating solution container 4 is provided with an auxiliaryheat-exchange circulating solution container 14 coupled thereto; and aheating device 15 such as a heater is disposed in the auxiliaryheat-exchange circulating solution container 14 or on the outer wallthereof.

The auxiliary heat-exchange circulating solution container 14 maypreferably be disposed in a portion other than the gas-liquid two-phasefluid charging pipe between the container 4 and the heating heatexchanger 11, and should merely be disposed in such a way as tocommunicate with the container 4. In FIG. 4, the auxiliary heat-exchangecirculating solution container 14 is communicated with the lower portionof the container 4; however, the constitution is not limitation to thatillustrated in FIG. 4.

In Embodiment 2, by providing the auxiliary heat-exchange circulatingsolution container 14 and by controlling the temperature inside thecontainer 14 by means of the heating device 15, the pressure inside theheat-exchange circulating solution container 4 can be adjusted, wherebythe boiling temperature of the heating heat exchanger 11 can becontrolled. As a result, the temperature of the heating heat exchanger11 can be adjusted.

Moreover, by controlling the temperature inside the container 14 bymeans of the heating device 15, the retained volume of the heat-exchangecirculating solution 1 in the container 14 can be adjusted, whereby theretained volume of the heat-exchange circulating solution 1 in theheat-exchange circulating solution container 4, or even the area, of theouter wall of the inner-container pipe 7, having contact with the vapor12 (the area in which condensation is produced) can be varied; inconsequence, the thermal resistance can be controlled through the outerwall of the inner-container pipe 7, whereby the total thermal resistanceof the system according to the present invention can be controlled.

In addition, in the present embodiment, the adjustment of the pressureinside the container 4 by means of expansion and contraction of thenoncondensable gas, such as air, enclosed in the container 14 may alsobe performed.

Moreover, with the heating device 15 disposed on the outer wall of thecontainer 14, covering the inner wall of the container 14 with poroussubstances such as wire gauze keeps the inner wall of the container 14wet by the heat-exchange circulating solution 1, thereby prevents thetemperature hike due to the container 14 being dried.

Still moreover, with a peltier device provided as the heat radiator 2,changing the value and the direction of an electric current supplied tothe peltier device makes possible heat radiation or heating, whereby thetemperature inside the heat-exchange circulating solution container 4can be controlled. As a result, as is the case with the foregoingembodiment, the pressure inside the heat-exchange circulating solutioncontainer 4 can be adjusted, whereby the same effect can bedemonstrated. Furthermore, providing a heater on the outer wall of theheat-exchange circulating solution container 4 can control throughheating by the heater the temperature inside the heat-exchangecirculating solution container 4, whereby the same effect can bedemonstrated.

Embodiment 3

FIG. 5 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 3 of the present invention.In the present embodiment, as illustrated in FIG. 5, the heat-exchangecirculating solution container 4 is provided with twocirculating-solution transporting pipes A. Providing twocirculating-solution transporting pipes A increases theheat-transferring area and decreases the thermal resistance. Inaddition, the heat transportation from scattering high-temperature heatsources, or to scattering low-temperature heat sources is facilitated.Moreover, because the heat-exchange circulating solution container 4 canbe shared by a plurality of circulating-solution transporting pipes A,the water-cooling system can be downsized in comparison to that whereina plurality of heat transportation apparatuses is provided.

Embodiment 4

FIG. 6 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 4 of the present invention.In the present embodiment, as illustrated in FIG. 6, the portion, of thegas-liquid two-phase fluid charging pipe 9, on which the heating heatexchanger 11 has been provided, the portion, of the solution dischargingpipe 6, on which the sensible-heat-emitting heat exchanger 10 has beenprovided, and the inner-container pipe 7 are divided by means of adistributing vessel 16 a and a collecting vessel 16 b, whereby aplurality of divided circulating solution transporting pipes isconstituted.

This manner increases the heat-transferring area and decreases thethermal resistance. This manner also facilitates heat recovery fromplane-surface, curved-surface, and formless fluid. In addition, makingthe plurality of divided circulating solution transporting pipes intonarrow tubes can raise heat transfer, and even heat transfercharacteristics.

FIG. 7 is a cross-sectional schematic view illustrating anotherpump-free water-cooling system according to Embodiment 4 of the presentinvention. In FIG. 7, the portion, of the gas-liquid two-phase fluidcharging pipe 9, on which the heating heat exchanger 11 has beenprovided is divided by means of two distributing vessels 16 a and twocollecting vessels 16 b into two gas-liquid two-phase fluid chargingpipes on which respective heating heat exchangers 11 are disposed inparallel. The two collecting vessels 16 b are connected directly to thecirculating solution container 4 that functions as another collectingvessel. In the case of this constitution, the heat-exchange circulatingsolution 1 may not pass through the solution outlet 5, but may passthrough any one of the heating heat exchangers and flows into anotherheating heat exchanger. In particular, with a non-heating heat exchangeraccompanied, the heat-exchange circulating solution 1 may be refluxed tothe heat-exchange circulating solution container 4 after departing fromthe heat-exchange circulating solution container 4 and then passingthrough the boiling heating heat exchanger by way of the non-heatingheat exchanger. In order to prevent this reflux, as illustrated in FIG.7, non-return valves 33 may be provided at respective upper-flowpositions of the divided gas-liquid two-phase fluid charging pipes.

In addition, in FIG. 7, the non-return valves 33 are provided atupper-flow positions; however, they may be provided at lower-flowpositions.

Moreover, In FIGS. 6 and 7, also when the system is constituted in sucha manner that the heating heat exchangers 11 are disposed in parallel onthe respective gas-liquid two-phase fluid charging pipes divided by thedistributing vessel 16 a (or a plurality of gas-liquid two-phase fluidcharging pipes), and that the divided plurality of the gas-liquidtwo-phase fluid charging pipes (or the plurality of gas-liquid two-phasefluid charging pipes) are connected directly to the heat-exchangecirculating solution container 4 without utilizing the collecting vessel16 b (the heat-exchange circulating solution container 4 functions as acollecting vessel), the non-return valves 33 may be provided atrespective upper-flow or lower-flow positions of the divided gas-liquidtwo-phase fluid charging pipes (or the plurality of gas-liquid two-phasefluid charging pipes).

Still moreover, FIG. 8 is a cross-sectional schematic view illustratinganother pump-free water-cooling system according to Embodiment 4 of thepresent invention. FIG. 8 (b) is a cross-sectional view of the system inFIG. 8 (a), as viewed along B-B. As illustrated in FIG. 8, by making thesystem to be an integral structure wherein the heat-exchange circulatingsolution container 4 is horizontally elongated, and the distributingvessel 16 a and the collecting vessel 16 b for the inner-container pipes7 are disposed at the both ends thereof, the structure and itsproduction can be simplified, whereby the cost is reduced. In addition,due to the heat-exchange circulating solution container 4 being madehorizontally elongated, the head-pressure change in the inner-containerpipe 7 is decreased, whereby the vapor bubbles 13, in theinner-container pipe 7, produced by the change in the head pressure isnot likely to occur; as a result, the pulsation of the circulating flowvolume of the heat-exchange circulating solution 1 is not likely tooccur, whereby provision is made for performing stable heattransportation. Moreover, FIG. 9 is a cross-sectional schematic viewillustrating another pump-free water-cooling system according toEmbodiment 4 of the present invention. As illustrated in FIG. 9, byproviding a great number of openable and closable connecting ports(e.g., one-touch connectors) 17 along both the distributing vessel 16 aand the collecting vessel 16 b, the third route portions with theheating heat exchangers 11 provided thereon can be attached or detached,whereby the constitution of the pump-free water-cooling system can bemodified depending on the purposes. In addition, even when the system isin operation, the constitution thereof can be modified. Also in thesystem constituted as illustrated in FIG. 6, by providing a great numberof openable and closable connecting ports (e.g., one-touch connectors)17 along both the distributing vessel 16 a and the collecting vessel 16b, the first route portion with the sensible-heat-emitting heatexchanger 10 provided thereon or the third route portions with theheating heat exchangers 11 provided thereon can be attached anddetached, whereby the constitution of the pump-free water-cooling systemcan be modified depending on the purposes. In addition, even when thesystem is in operation, the constitution thereof can be modified.

Moreover, as illustrated in FIG. 9, a degassing outlet 18 provided onthe heat-exchange circulating solution container 4 enablesnoncondensable gas that enters therethrough upon the constitutionalmodification or noncondensable gas that has been initially contained tobe discharged, whereby the deterioration of the heat characteristics canbe prevented.

Embodiment 5

FIG. 10 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 5 of the present invention.In the present embodiment, as illustrated in FIG. 10, thecirculating-solution transporting pipe A includes a single gas-liquidtwo-phase fluid charging pipe 9, a single solution discharging pipe 6,two inner-container pipes 7 and 7 a, and a single first outer-containerpipe (the fourth route) 6 a provided between the two inner-containerpipes 7 and 7 a. The first outer-container pipe 6 a is provided with thesame sensible-heat-emitting heat exchanger 10 as that provided on thesolution-discharging pipe 6.

This manner increases the heat-exchanging areas of inner-container pipes7 and the portion around the sensible-heat-emitting heat exchanger 10,thereby decreases the thermal resistance.

Making the circulating-solution transporting pipe A into furtherparallel flowing paths by means of two or more first outer-containerpipes 6 a and three or more inner-container pipes 7 and 7 a can decreasethe frictional pressure loss during one-cycle circulation through thecirculating-solution transporting pipe A, whereby the circulating flowvolume of the heat-exchange circulating solution 1 can be increased (thesensible-heat-transporting volume increases). As a result, the totalthermal resistance is decreased; therefore, despite small difference intemperature between the heating heat exchanger 11 and thesensible-heat-emitting heat exchanger 10, a large amount of heat can betransported. This manner further facilitates heat recovery or heatradiation from or to a planar surface of a solid, curved-surface fluid,formless fluid, or the like.

In addition, in the foregoing embodiment, different-types of thesensible-heat-emitting heat exchangers 10 and 10 a may be provided onthe solution discharging pipe 6 and the outer-container pipe 6 a,respectively.

In the present embodiment, the inner-container pipe 7 a other than theinner-container pipe 7 that is closest to the heating heat exchanger 11may not pass through the heat-exchange circulating solution container 4and may be provided with another heating heat exchanger 11 a. In otherwords, as illustrated in FIG. 11, the second outer-container pipe (thefifth transportation route) 7 b provided with the heating heat exchanger11 a and the sensible-heat-emitting heat exchanger 10 a may be disposedbetween the inner-container pipe (the second transportation route) 7 andthe solution discharging pipe (the first transportation route) 6. Inaddition, a plurality of the second outer-container pipes (the fifthtransportation route) 7 b may be provided.

In this manner, the heat recovery or the heat transportation from or tothe scattered heat sources can readily be performed with a singleheat-exchange circulating solution container 4; and the system can bedownsized.

Moreover, if the amount of heat exchanged by the heating heat exchanger11 a is smaller than that exchanged by the heating heat exchanger 11,and the heat-exchange circulating solution 1 within the secondouter-container pipe on which the heating heat exchanger 11 a isprovided does not boil, the heating heat exchanger 11 a can be disposedabove the heat-exchange circulating solution container 4, whereby thedegree of freedom in the location of the heating heat exchanger hikes.

The control of the heating heat exchanger 11 (e.g., controlling fromoutside the electric power supplied to a heater that is disposed as theheating heat exchanger 11) can adjust the circulating flow volume of theheat-exchange circulating solution 1, whereby not only heat can betransported from another heating heat exchanger 11 a, but also thetemperature of the heating heat exchanger 11 a can be adjusted.

In addition, as described above, by disposing the heater as the heatingheat exchanger 11, the positional limitation between an object ontowhich heat is transported (e.g., an electronic apparatus) and theheating heat exchanger 11 is eliminated; therefore, the heating heatexchanger 11 can even be disposed further lower. In this manner, thebuoyant force for driving the heat-exchange circulating solution canmore effectively be obtained, whereby the heat characteristics hike.

Moreover, as illustrated in FIG. 12, by constituting a bubble pumpmodule 27 (in the module 27, the heating heat exchanger 11 is situatedunder the heat-exchange circulating solution container 4) that containsthe heat-exchange circulating solution container 4, the heat radiator 2,the solution outlet 5, the inner-container pipe 7, the gas-liquidtwo-phase fluid charging pipe 9, the gas-liquid two-phase fluid inlet 8,and the heating heat exchanger 11 with a heater thereon, the limitationto the installation position of the module 27 is eliminated; inconsequence, provision is made for further free arrangement. Utilizationof the module 27 as a general-purpose article reduces the cost of thesystem.

In FIG. 12, the heating heat exchanger 11 a is disposed in the vicinityof an electronic component situated within a case 29, and the module 27and a plurality of the sensible-heat-emitting heat exchangers 10 and 10a are disposed outside the case 29. Regardless of the mounting positionof the electronic component, the heating heat exchanger 11 a can bedisposed in the vicinity of the electronic component; therefore, theheat emanating from the electronic component within the case can readilybe transported outside the case.

Embodiment 6

FIG. 13 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 6 of the present invention.In the present embodiment, as illustrated in FIG. 13, a auxiliary heater21 is provided along the gas-liquid two-phase fluid charging pipe 9.

In this manner, even when the temperature difference between the heatingheat exchanger 10 and the sensible-heat-emitting heat exchanger 11 issmall, and the heat-exchange circulating solution 1 in the heating heatexchanger 10 does not boil, boiling in the heating heat exchanger 10 canbe produced by supplying the auxiliary heater 21 with electricity,thereby heating it. This way enables the heat-exchange circulatingsolution 1 to circulate through the solution circulating pipe A, wherebyheat can be transported even when the temperature difference is small.

If the heating heat exchanger 11 is situated horizontally, reverse flowor pulsation of the heat-exchange circulating solution 1 could occur,but operating the system with the auxiliary heater 21 provided on therising portion of the gas-liquid two-phase fluid charging pipe 9 allowsthe heat-exchange circulating solution 1 to circulate normally, wherebystable start-up and heat transportation can be performed. In addition,in this case, operation of the auxiliary heater 21 only duringactivation is possible.

Moreover, the installation location for the auxiliary heater 21 may bebelow or above the heating heat exchanger 11, as illustrated in FIG. 13,so long as it is a portion in which the solution in the gas-liquidtwo-phase fluid charging pipe 9 rises.

Still moreover, in the case where the auxiliary heater 21 is providedbelow the heating heat exchanger 11, the heat-exchange circulatingsolution 1 flowing into the heating heat exchanger 11 is preheated,whereby the difference between the temperature of the solution 1 at theinlet of the heating heat exchanger 11 ant the saturation temperature ofthe solution 1 becomes smaller. Therefore, subcooled boiling, whichoccurs when the pressure in the system is small, and the resultantpulsation of the circulating flow volume, vibration, and noise hardlyoccurs.

In this case, the auxiliary heater 21 preferably is provided in such amanner that the more downstream the position along the flowing pathprovided the auxiliary heater 21 is, the larger the heated flux is.

In addition, bubble nuclei may be provided in the inner wall of theportion on which the auxiliary heater 21 is provided, or in the innerwall of the portion on which the heating heat exchanger 11 is provided.Bubble nuclei, which play a role in stably keeping gas remaining in theinner walls or in the fluid path, regardless of the flow and oragitation in the fluid and of temperature change of the fluid and thepath wall, are, as illustrated in FIG. 14( a), scratches 22 provided inthe inner-wall surface A1 of a pipe or, as illustrated in FIG. 14( b),spaces (reentrant-type cavities) 24 communicating to the fluid (theheat-exchange circulating solution) 1 through a narrow channel 23. Sucha recess as illustrated in FIG. 14 may be formed by means of amechanical or chemical process, or may be formed by covering the innerwall with wire mesh. In addition, as illustrated in FIG. 15, bubblenuclei 26 may be formed by sintering or bonding metal powder 25 onto theinner-wall surface A1.

This constitution, even when the pressure in the system is low due tothe low temperature thereof, makes gas to remain in the bubble nucleistably, it expands and a part of one breaks away from the surface A1continuously, whereby the vapor bubbles 13 can readily be generated;therefore, the system can easily be activated, and also the heatcharacteristics on the surface A1 are enhanced.

Embodiment 7

FIG. 16 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 7 of the present invention.In the present embodiment, as illustrated in FIG. 16, the solutionoutlet 5 and another solution outlet 5 a are provided respectively atthe left and right ends of the heat-exchange circulating solutioncontainer 4, and respective solution discharging pipes 6 are linked withthese solution outlets 5 and 5 a, and join along their ways, connectingto the inner-container pipe 7.

In cases where a pump-free water-cooling system is mounted in anautomobile, due to effects of inclination and gravity, the gas-liquidinterface of the heat-exchange circulating solution 1 in theheat-exchange circulating solution container 4 may fluctuate, whereuponthe solution outlet 5 could be exposed in a space containing vapor. Inthis situation, because vapor could be taken in by the solutiondischarging pipe 6, the smooth circulation of the heat-exchangecirculating solution 1 could be hindered, whereby the heattransportation characteristics could deteriorate. In order to addressthis, according to the present embodiment, by constituting a pump-freewater-cooling system in such a manner that a plurality of solutionoutlets 5 and 5 a are provided in the heat-exchange circulating solutioncontainer 4, and the respective solution discharging pipes 6 link withthe plurality of solution outlets, and the linking portions join,connecting to the inner-container pipe 7, the system becomesinsusceptible to the effects of left-and-right and back-and-forthinclinations, and of volumetric force (e.g., gravity).

Embodiment 8

FIG. 17 is a perspective view illustrating a pump-free water-coolingsystem according to Embodiment 8 of the present invention; and FIG. 18is a cross-sectional schematic view illustrating the heating heatexchangers 11 and a rack wall 19 involving Embodiment 8 of the presentinvention. In Embodiment 8, a pump-free water-cooling system is appliedto a rack for containing an electronic apparatus (e.g., such as aboard-type server) 20, and is installed in such a manner that theheating heat exchangers 11 function as the mounting walls for theelectronic apparatus. This way enables the heat produced by theelectronic apparatus 20 to be transported and radiated, whereby theelectronic apparatus 20 can be kept under its allowable temperature.

In addition, it is advisable to carry out the inserting of thermalsheets or the coating of thermal grease on the contact faces between theheating heat exchanger 11 and the electronic apparatus 20, in order todecrease the contact thermal resistance.

Moreover, as illustrated in FIG. 18, by tapering the contours of theheating heat exchanger 11 and the electronic apparatus 20, contactpressure can be obtained adequately, whereby the contact thermalresistance can be reduced.

Still moreover, the heating heat exchanger 11 may be provided on upperor bottom surface instead of on the sidewalls of the electronicapparatus 20.

Embodiment 9

FIG. 19 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 9 of the present invention.In the present embodiment, as illustrated in FIG. 19, the heat radiator2 and the sensible-heat-emitting heat exchanger 10 are provided abovethe ceiling of a case 29 or the like. In general, in cases where theheat radiator 2 is provided on the case 29, it is probable that thespatial height over the top portion of the case 29 will be limited.While, the latent heat transport system as heat pipes requires the largeinstallation clearance, especially the higher spatial height, for thecondenser of the system. Thus, the above limitation makes the latentheat transport system difficult to use as cooling system for electronicapparatus in the case 29. However, in the present invention, because thesensible-heat-emitting heat exchanger 10 that can be installed in anyplace is provided, heat can be radiated by means of thesensible-heat-emitting heat exchanger 10; therefore, usable installationspace, above the case 29, having a low spatial height, but being largecan effectively be utilized. As a result, heat can more effectively beradiated.

Embodiment 10

FIG. 20 is a cross-sectional schematic view illustrating a pump-freewater-cooling system according to Embodiment 10 of the presentinvention, in cases where the system is applied to cooling for anelectronic apparatus such as a personal computer. Personal computersthat are now in use generate a large amount of heat; therefore,forced-air-cooling heat radiation utilizing a fan has been adopted.Although the quietness performance of fans has been improved day by day,further quietness performance is being demand.

In the present embodiment, as illustrated in FIG. 20, thesensible-heat-emitting heat exchanger 10 is provided in a clearance inthe vicinity of the sidewall, or inner bottom portion, of a personalcomputer 32, or the like, while a heat-generating component, such as amother board 30, a CPU 31, or a memory, is disposed on the gas-liquidtwo-phase fluid charging pipe 9.

In this manner a fan is eliminated, and furthermore heat can effectivelybe radiated.

As a result, a fun-free heat-radiating system can be constituted,whereby a low-noise personal computer can be provided.

As this invention may be embodied in several forms without departingfrom the spirit of the essential characteristics thereof, the presentembodiments are therefore illustrative and not restrictive, since thescope of the invention is defined by the appended claims rather than bythe description preceding them, and all changes that fall within themetes and bounds of the claims, or the equivalence of such metes andbounds, are therefore intended to be embraced by the claims.

1. A pump-free water-cooling system, comprising: a heat-exchangecirculating solution container in which heat-exchange circulatingsolution, vapor of the circulating solution, and noncondensable gas canbe contained; a solution outlet to discharge from the container theheat-exchange circulating solution in the container; a gas-liquidtwo-phase fluid inlet to charge into the container gas-liquid two-phasefluid composed of the heat-exchange circulating solution at hightemperature and vapor bubbles of the circulating solution; a firsttransportation route along which a sensible-heat-emitting heat exchangeris provided, the first transportation route being linked with thesolution outlet; a second transportation route along which heat exchangeis carried out between heat-exchange circulating solution therein andthe heat-exchange circulating solution in the container, or between theheat-exchange circulating solution therein and the heat-exchangecirculating solution in the container and the vapor of the heat-exchangecirculating solution in the container; a third transportation routealong which a heating heat exchanger is provided, the thirdtransportation route being linked with the gas-liquid two-phase fluidinlet; and a circulating-solution transporting route in which the firsttransportation route is linked to the second transportation route andthe second transportation route is linked to the third transportationroute.
 2. A pump-free water-cooling system, as recited in claim 1,wherein the noncondensable gas is air.
 3. A pump-free water-coolingsystem, comprising: a heat-exchange circulating solution container inwhich heat-exchange circulating solution and vapor of the circulatingsolution can be contained; solution outlets to discharge from thecontainer the heat-exchange circulating solution, wherein the solutionoutlets are provided at both ends of the container; a gas-liquidtwo-phase fluid inlet to charge into the container gas-liquid two-phasefluid composed of the heat-exchange circulating solution at hightemperature and vapor bubbles of the circulating solution; a firsttransportation route along which a sensible-heat-emitting heat exchangeris provided, the first transportation route being linked with each ofthe solution outlets; a second transportation route along which heatexchange is carried out between heat-exchange circulating solutiontherein and the heat-exchange circulating solution in the container, orbetween the heat-exchange circulating solution therein and theheat-exchange circulating solution in the container and the vapor of theheat-exchange circulating solution in the container; a thirdtransportation route along which a heating heat exchanger is provided,the third transportation route being linked with the gas-liquidtwo-phase fluid inlet; and a circulating-solution transporting route inwhich the first transportation route is linked to the secondtransportation route and the second transportation route is linked tothe third transportation route.